Improvement in drawing-boards



A. HITCHCOCK, Drawing-Boards.

"0.139507. Patente djune3,l873.-

[222/622 afar .when in place, revolves.

UNITED STATES ALONZO HITGHCOCK,

OF NEW YORK, N. Y.

IMPROVEMENT IN DRAWING-BOARDS.

Specification forming part of Letters Patent No. 139,507, dated June 3,1873 application filed September 27, 11:71.

To all whom it may concern:

Be it known that I, ALONZO Hrronooox, of the city, county, and State ofNew York,

Y have invented a new and useful Improvement in RevolvingDrawing-Boards, of which the following is a specification, referencebeing had to the accompanying drawings, forming p..rt of the same.

Figure 1, Sheet I, is a top face view of a revolving board embodying myimprovements; Fig. 2, same sheet, is an elevation of the same; Fig. 3 ofthe same sheet is a face of the under side of the drawing-board; Fig 4,Sheet II, is a top view of the frame, with its attachments, on which thedrawing-board is mounted; Fig. 5, same sheet, is a central verticalsectiona'l view of my drawing-board mounted on its frame; Fig. 6, samesheet, is an end view of the same.

M yinvention relates to a revolving drawingboard, constructed ashereinafter particularly described, the same consisting of a tablepivoted in the center upon a portable frame and having combined with ita fixed graduated rest, and the mechanism described for stopping andholding the revolving board in certain fixed positions, and on its facea graduated circle located off from the pivotal center of the board.

A is a drawing-board, which may be of any suitable dimensions and form;B is a frame, preferably made of irons, on which the board is mounted; Uis a fixed rest and graduated scale, mounted upon the ends of the armsa, extending out from one side of the frame. Upon the under side of theboard A is fixed the graduated and indented disk or circle I), made ofmetal, in the center of which is the pivotal post or pin I), upon whichthe board, In the center of the cross-bar c of the frame B is a socket,d, fitted to receive the post I), and upon which the board may revolve,resting on the base 0. The board is held in place by a pin through thelower end of the post b. The socket may be on the circle D and the pinon the frame. E is a lever pivoted in post f, connected with the frame.Upon the inner end of this lever is a bevel-edged pin, 03, and thespring 9 presses the end of the lever upward against the board when inplace, thus forcing the pin against the indented circle D. The oppositeend of this lever is furnished with a catch, h, that is pressed up tothe lever by the spring k. When the board is in place on' its frame itis evident that it may be rotated at, pleasure, and adjusted to anyrequired position,

by lifting the opposite end so that it is held by the catch it. Whenthus adjusted the lever may be liberated from .the catch, when the pin2' will be pressed upward by the spring 9 against the board, or ratherthe circle I), thus fixing it in position. The circle may have in itsface any number of indentations or creases, graduated to mark givenangles, into which the pin 6 may enter, whereby the board may, withoutmeasurement at the moment, he set to any angle on the said circle. FFare graduated circles drawn upon or affixed to the face of the board,off from the. center, not concentric to it nor embracing the centerwithin it. Placing these graduated circles thus away from the centergives the opportunity of fixing the paper upon which the N drawing is tobe done upon the board, Without covering them up. From these graduatedcircles, by means of the fixed rest U and a T-square, any required anglefor drawing may be taken.

The operation is as follows: Adjust the board, .having the drawing-paperproperly attached, with one end parallel to the fixed rest. After thefirst or base line of thedrawing is made at right angles to the fixedrest, and any given angle to that line is required to be drawn, turn theboard until the radial line on the circle F, vhich indicates such angle,is parallel with the T-square when adjusted to the fixed rest, and inthat position the T-square held to the fixed rest will give therequisite angle in the drawing. It is evident thatthe use of'thesenoncon centric circles, and the mechanism l have described for holdingthe board in position, will obviate the necessity for a great -deal ofmeasurement with dividers and scales in drawing, and save much time WhatI claim as my invention, and desire to secure by Letters Patent, is-

A revolving drawing-table, composed of the board A, the portable frameB, the fixed rest G, the catch h, and the graduated circle F F, one orboth, all constructed, combined,-

